Seriatopora hystrix

Seriatopora hystrix, the thin birdsnest coral, is a colonial stony coral in the family Pocilloporidae that forms a tangled, bushy clump of fragile, tapering branches with pointed tips. Colonies can grow to about a metre across and may be cream, pink, yellow, brown or blue. Its type locality is the Fiji Islands, and it ranges from East Africa, Madagascar and the Red Sea through the Indian Ocean to tropical Australia, Japan, the South China Sea and the western and central Pacific, mostly on reefs and reef flats at 3 to 15 metres. Each polyp is both male and female, and larvae are brooded and settle within about a day, so many land close to the parent colony. The coral houses symbiotic dinoflagellates, shelters crabs and shrimps that guard it from predators, and can reproduce asexually when fragments break off or when stressed polyps bail out of a dying colony. Ocean acidification, climate change and habitat loss threaten it, it is collected for the reef aquarium trade, and the IUCN lists it as Vulnerable.